ginkgo.Jenkinsfile: reduce VM boot and provision timeout to 30 minutes
ginkgo.Jenkinsfile: reduce VM boot and provision timeout to 30 minutes

Now that we cache Vagrant boxes locally in our CI, we can reduce the time the
provisioning / booting stage takes. The longest provisioning time recently was
around 13 minutes, so 30 minutes provides a good cushion for any variability
beyond the longest most recently observed duration for the stage.

Signed-off by: Ian Vernon <ian@cilium.io>

tklauser/cilium,tklauser/cilium,cilium/cilium,michi-covalent/cilium,tgraf/cilium,cilium/cilium,michi-covalent/cilium,cilium-team/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium,cilium-team/cilium,tgraf/cilium,michi-covalent/cilium,tklauser/cilium,michi-covalent/cilium,tgraf/cilium,tklauser/cilium,tgraf/cilium,tklauser/cilium,tgraf/cilium,cilium/cilium,tgraf/cilium